Those incumbent presidents were all seriously challenged – and seriously weakened – by insurgent candidates within their own party. LBJ was so jolted by antiwar Democrat Eugene McCarthy’s strong primary showing that he decided to junk his bid for renomination.

Ford barely survived a Republican primary challenge on his right flank, from Ronald Reagan, and lost his re-election race. Carter weathered an acrimonious Democratic challenge on his left flank, from Edward Kennedy, and lost his re-election race. The senior Bush was beaten up badly by a challenge on his right flank, from Pat Buchanan, and lost his re-election race.

That’s my way of saying that former tea-party congressman Joe Walsh – who joined the GOP presidential race this week as a vehicle for Republican primary voters who are fed up with Donald Trump – should not be dismissed out of hand.

No, he won’t wrest the nomination away from Trump, but Walsh is a rhetorical brawler who’s willing to say out loud what he believes many Republicans whisper in private. A challenger on Trump’s right flank is arguably the only person who can make the case to Trump’s base.

“The country is sick of this guy’s tantrum. He’s a child…He’s nuts. He’s erratic. He’s cruel. He stokes bigotry. He’s incompetent. He doesn’t know what he’s doing. He’s a narcissist,” Walsh said on ABC’s “Right now he is literally tweeting us into a recession. He will tweet us into war.”

It’s not entirely clear when Walsh broke with Trump. Granted, he says now that “I helped to create Trump, I’m sorry for that.” But as recently as last year, he defended Trump’s denigration of some non-white nations as “s—holes.” He also assailed immigrants at the Mexican border as “invaders” and prior to Trump’s ascent, he had a habit of referring to President Obama as “a Muslim.”

In other words – and what a shock – Walsh is an imperfect messenger. Conservative websites are gleefully compiling his past bombastic statements, and Democrats are stewing about them. But let’s get real: There is no perfect messenger.

A disenchanted former Trump supporter is arguably the best possible candidate for grassroots Republicans, and Republican-leaning independents, who’d consider casting protest votes during primary season. Potentially, they could use Walsh’s ballot line to send a much-needed message about what Republicans have lost as a party, and what they hope to regain.

Sarah Longwell, publisher of The Bulwark, a conservative anti-Trump website, wrote in a Twitter thread that Walsh’s candidacy could be “a path forward” for people on the right who still adhere to civility and American values.

Because what Joe Walsh is doing is what we hope every Trump supporter will do, right? Say that their support or even silent toleration of Trump’s racism, incompetence, and bullying was wrong and make an affirmative decision to refuse to allow it to go any further.

She said, “There must be a moment when the spell breaks (and) the rationalizations stop. And there is a clear-eyed reckoning with who we’ve become…Because what Joe Walsh is doing is what we hope every Trump supporter will do, right? (To) say that their support or even silent toleration of Trump’s racism, incompetence, and bullying was wrong, and make an affirmative decision to refuse to allow it to go any further.”

Joe Walsh will face many obstacles, everything from name recognition (no, this is not the Joe Walsh who played guitar for The Eagles) to the challenge of raising money. But in political time, we’re light years away from Iowa and New Hampshire, and the odds are strong that Trump will say or do things that will feed Walsh’s simple message to silent Republicans: “We’re tired of the lies. We’re tired of the drama.”

Capital-Star Opinion contributor Dick Polman is the national political columnist at WHYY-FM in Philadelphia and a “Writer in Residence” at the University of Pennsylvania. His work appears on Mondays on the Capital-Star’s Commentary Page. Readers may email him at [email protected].